Flexible Transfer Machine

ABSTRACT

The invention relates to a transfer machine for the successive machining of work pieces, comprising at least two machining stations and work piece supports which are used to receive work pieces ( 33 ), comprising receiving positions ( 52, 38, 39, 40 ) and deposit positions ( 38, 39, 40, 41 ) for the work pieces ( 33 ). The work piece supports ( 25, 26, 27, 28 ) are disposed in a displaceable manner between the receiving, positions ( 52, 38, 39, 40 ), the working area of the at least two machining, stations ( 1, 2, 3, 4 ) and the deposit positions ( 38, 39, 40, 41 ).

The invention relates to a transfer machine for the successive machiningof workpieces, comprising at least two machining stations and workpieceholders.

Transfer machines are known in practice in many variations. They arelinked together,, for example, by cyclically operating conveying means,such as in the form of rails or transfer bars. In the machines, themachining units are disposed transverse to the feed device. Before aworkpiece can perform the next cycle and be replaced by an unmachinedpiece, the corresponding machining unit must be moved to an idleposition. It can only resume its working position when the unmachinedworkpiece has been positioned and clamped in place. Because of thisoperating scheme, this mode of operation results in significantnonproductive periods. To reduce the nonproductive time, DE 37 22 180provides clamping devices opposite one another on both sides of theconveying device.

While one clamping device is being loaded and unloaded, the workpiececlamped in the other clamping device is being machined.

From DE 41 42 121 A1 (Translator's note: U.S. Pat. No. 5,361,485), weknow of a transfer machine for machining differential housings. In themachining stations, work rests comprising clamping and locatingmechanisms are provided for the workpieces, the contact areas at whichthe locating surfaces come in contact with the workpieces being the samein every machining station. This transfer machine is configuredspecifically for machining differential housings.

It is the object of the present invention to provide a flexibleconfiguration of a transfer machine for machining various workpieces. Itis also the object of the invention to reduce the structural complexityand space requirement of the machines and reduce the cycle time requiredfor machining the workpieces.

The core idea of the invention is to transport the workpieces on atransfer machine according to the pick-up principle from one machiningstation to the next.

As a result, all machining stations are integrated in a base machinebody, which may be configured in a one-part or multipart design. Thebase machine body comprises at least one support wall. An advantageousembodiment basically includes two support walls that areconnected-together by connecting webs. The base body may likewise beconfigured in a section extending orthogonally to the longitudinal axisof H-, L- or U-shape. The base machine body may be configured as onepiece or comprise several sections that are joined in a row as needed.In a particularly advantageous embodiment, common guide rails areprovided on the base machine body for the workpiece holders above themachining stations, on which rails horizontal carriages are guided forhorizontal displacement. The horizontal carriages in turn carry verticalguides for accommodating vertically shiftable carriages. The verticallyshiftable carriages receive the workpiece holders. The workpiece holdersare provided with devices for the direct gripping, clamping andtransporting of workpieces. In a further embodiment of the invention,the workpieces are fixed in clamps, so-called pallets, that theworkpiece holders can accommodate. In the machining stations, therequired tools, particularly motor-driven tools for drilling, milling,grinding, deburring etc., are provided. In an advantageous embodiment,the tools, particularly multispindle drill heads, are provided on theconnecting webs of the base machine. body. Likewise, motor-driven toolsmay be provided in turrets. According to a further embodiment of theinvention, the motor-driven tools may be pivoted about an axisorthogonal to the transport direction. The pivot bearings and the drivemechanism for the pivot motion are accommodated in the support walls ofthe base machine-body. Alternately, a pivoting device may be provided onthe workpiece holder for pivoting the workpieces.

So as to be able to move the workpiece holder parallel to a secondhorizontal axis, first and second horizontal carriages are providedaccording to an advantageous embodiment. Alternatively, the machiningunit may be mounted for displacement in the direction of the Y-axis onguides of the base machine frame.

The unmachined workpieces are moved into the effective range of thefirst workpiece holder using a conveyor. The workpiece holders grab theworkpiece and feed it to the first machining station for machiningpurposes. Following the machining operation, the workpiece is placed ina transfer station and taken over from there by the second workpieceholder. Optionally, the workpiece is fed to further machining stationsuntil all machining steps have been performed. At the end, the workpieceis placed on an output station and moved out of the effective range ofthe last machining station.

In the transfer machine according to the invention, the transport of theworkpiece is implemented via the axes of displacement that are providedin any case for feeding the workpieces. As a result, conventionaltransport systems can be eliminated and the machining stations can beintegrated into a base machine body.

The invention will be explained in more detail hereinafter based onillustrated embodiments:

FIG. 1 is a sectional view of a transfer machine according to theinvention,

FIG. 2 shows the cross-section of a transfer machine,

FIG. 3 shows the cross-section of a transfer machine with a Y-axis onthe workpiece holder,

FIG. 4 shows a machining station with Y-axis in the base machine frame,

FIG. 5 shows a pivoting machining station,

FIG. 6 shows a workpiece holder with pivoting device,

FIG. 7 shows a base machine body with L-shaped cross-section.

FIG. 1 shows a transfer machine with four machining stations. Dependingon the number of required machining steps, however, the number ofmachining stations may also be higher or lower. The machining stations1, 2, 3, and 4 are integrated in a base machine body 5., It is formedbasically by two longitudinal support walls 6 and 7 that are connectedtogether by transverse webs 8, 9, 10, and 11. Workpiece holders 25, 26,27, and 28 ride on common guide rails 13 and 14 provided on the basemachine body 5 above the machining stations 1, 2, 3, and 4, on whichrails horizontal carriages 15, 16, 17, and 18 are guided horizontallydisplaceably. The horizontal carriages 15, 16, 17, and 18 carry guideshoes 51 for guide rails 19 and 20 that vertically guide the workpieceholders 25, 26, 27, and 28. These are provided with clamps 29, 30, 31,and 32 for the detachable gripping of workpieces 33 to be machined. Inthe machining stations, the required tools 34, particularly motor-driventools for drilling, milling, grinding, deburring etc., are provided. Inan advantageous embodiment, multispindle drill heads 35 and 36 areprovided on the connecting webs 8, 9, 10, and 11 of the base machinebody 5. Likewise, motor-driven tools 34 may be provided in turrets. Theunmachined workpieces 33 are moved into the effective range of the firstworkpiece holder 25 using a conveyor 37. The workpiece holder 25 seizesthe workpiece 33 and feeds it to the first machining station 1 formachining purposes. Following the machining operation, the workpiece 33is placed in a transfer station 38 and taken over from there by thesecond workpiece holder 26. Optionally, the workpiece 33 is fed tofurther machining stations 2, 3, and 4 until all machining steps havebeen performed. The receiving, transfer and transfer stations 52, 38,39, 40, and 41 are provided with covers when the workpiece is beingmachined to protect it from contaminants. Following the last machiningstep, the workpiece 33 is placed in the output station 41 and taken outof the effective range of the machining station 4.

FIG. 2 shows a cross-sectional view of the transfer machine. The guiderails 13 and 14 for the horizontal carriages 15, 16, 17, and 18 areprovided at the top of the walls 6 and 7. The drive mechanism for thehorizontal carriages 15, 16, 17, and 18 is configured as a straight-linedrive 50. The walls 6 and 7 have openings 48 and 49 for incoming andoutgoing workpieces 33 and for operating and maintaining the machines.The workpieces are transported with the conveyor 37.

In an advantageous embodiment according to FIG. 3, first and secondhorizontal carriages 42 and 43 are provided, as a result of which theworkpiece holders 25, 26, 27, and 28 are displaceable in the horizontaldirection along two axes X and Y that run orthogonal to each other. Fordrive purposes a motor 53 is provided.

According to FIG. 4, one machining station is configured as a motorspindle 56 with the tool 34 for displacement in the direction of theY-axis. The spindle is displaceable on guides 54 in the base machinebody 5. The guides 54 can be oriented orthogonal to the main coordinateaxes of the machine system, or at any arbitrary angle.

According to a further embodiment of the invention in FIG. 5, themotor-driven tools 34 can be pivoted about a pivot axis 12 orthogonal tothe Z-axis. The pivot bearings 44 and 45 and the pivot drive mechanism46 are accommodated in the support walls 6 and 7 of the base machinebody 5.

In an equivalent fashion to FIG. 3, in FIG. 6 a horizontal carriage 42is provided on the base machine body 5. This carriage supports a secondcarriage 43 comprising guide rails 54 for accommodating the workpieceholder 25. The workpiece holder 25 is provided with a pivoting device 55for inclining the workpieces 33 about a pivot axis 12. The pivotingdevice 55 allows machining of the workpieces 33 at arbitrary angles.Furthermore, the clamping device 29 can be pivoted in a horizontalmachining position and in a vertical pick-up position 59. Themultispindle drill head 36 is likewise pivotable and can be pivoted fromthe horizontal machining position 60 into a servicing position 61. Inthe wall 6 of the base machine body 5, there is a recess 58 for theworkpiece holder 21.

FIG. 7 shows a base machine body 5 with L-shaped cross-section. Thevertical wall 6 carries the guides 13 and 14 for the horizontal carriage15. The base plate 57 forms the horizontal side in the L-shapedcross-section. A straight-line drive 50 is provided for driving thehorizontal carriage 15. It is positioned between the guides 13 and 14.

LIST OF REFERENCE NUMERALS

-   1, 2, 3, and 4 Machining Station-   5 Base Machine Body-   6 and 7 wall-   8, 9, 10, and 11 Connecting Web-   12 Pivot Axis-   13 and 14 Guide Rail-   15, 16, 17, and 18 Horizontal Carriage-   19 and 20 Guide Rail-   25, 26, 27, and 28 Workpiece holder-   29 Clamping Device-   33 Workpiece-   34 Tool-   35 and 36 MultiSpindle Drill Head-   37 Conveyor-   38, 39, 40 Transfer station-   41 Transfer station-   42 and 43 Horizontal Carriage-   44 and 45 Pivot Bearing-   46 Pivot Drive-   47 Transport Direction-   48 and 49 Opening-   50 Straight-line Drive-   51 Guide Shoe-   52 Input station-   53 Drive Mechanism-   54 Guide-   55 Pivoting Device-   56 Motor Spindle-   57 Base Plate-   58 Recess-   59 Pick-Up Position-   60 Machining Position-   61 Servicing Position

1. A transfer machine for the successive machining of workpieces,comprising at least two machining stations and workpiece holders,clamping devices for receiving the workpieces during the machiningoperation, an input station, at least one transfer station and atransfer station for workpieces, characterized in that the workpieceholders are mounted for displacement between the input station, at leastone transfer station, the effective range of at least two machiningstations, and the transfer station.
 2. A transfer machine for thesuccessive machining of workpieces, comprising at least three machiningstations and workpiece holders, fixtures for automatically gripping,clamping and transporting workpieces, an input station, at least twotransfer stations and a transfer station for workpieces, characterizedin that the workpiece holders are mounted for displacement between theinput station, at least two transfer stations, the effective range of atleast three machining stations and the transfer station.
 3. A transfermachine according to claim 1, characterized in that the transferstations of a previous workpiece holder at the same time serve as inputstations for a subsequent workpiece holder.
 4. A transfer machineaccording to claim 1, characterized in that the workpiece holders aremounted for displacement on common guides.
 5. The transfer machineaccording to claim 4, characterized in that the machining units and theworkpiece holders are mounted in a common base machine housing.
 6. Atransfer machine according to claim 1, characterized in that the toolsare mounted for pivoting about a pivot axis in a direction orthogonal tothe Z-axis.
 7. A transfer machine according to claim 1, characterized inthat a pivoting device is provided on at least one workpiece holder forpivoting the workpieces.
 8. A transfer machine according to claim 1,characterized in that at least one workpiece holder with a firsthorizontal carriage and a second horizontal carriage is mounted fordisplacement in the horizontal direction in two axes X and Y extendingorthogonal to each other.
 9. A transfer machine according to claim 7,characterized in that at least one tool is guided displaceably on thebase machine frame on guides in a direction at an arbitrary angle to theX and Z-axes.
 10. A transfer machine according to claim 7, characterizedin that at least one tool is guided displaceably on the base machineframe on guides in a direction orthogonal to the X and Z-axes.
 11. Atransfer machine according to claim 1, characterized in that amultispindle drill head is provided in at least one of the machiningstations.
 12. A transfer machine according to claim 1, characterized inthat the base machine frame comprises two support walls that areconnected to each other by connecting webs.
 13. The transfer machineaccording to claim 12, characterized in that the connecting webs receivethe machining units.
 14. The transfer machine according to claim 7,characterized in that the clamp can be pivoted in a horizontal machiningposition and in a vertical pick-up position.
 15. The transfer machineaccording to claim 11, characterized in that the multispindle drill headcan be pivoted from a horizontal machining position in a servicingposition.